Normal mode

Compact mode

-Tabs expand on hover.

Works best in Photon UI. Not tested with proton UI changes, but it is compatible.

Dark theme used - Light/dark grey & orange theme. Available from the Firefox add-ons store. UI may not be displayed correctly with other themes.

Tree style tabs extenstion required.

How to add stylesheets: https://winaero.com/enable-loading-userchrome-css-usercontent-css-firefox/

Put userChrome.css, userContent.css and newtabbgimg folder in the chrome folder of current active profile root folder. Put user.js in the current active profile root folder.

Copy the code in TST_advanced_section.css and paste it in the advanced section textbox of tree style tabs settings page.